Coincidence-telemeter.



O. EPPENSTEIN. GOINGIDENGE TELBMETER. APPLICATION FILED NOV.17, 1911.

1,021,306. Paten'td Mar. 26', 1912.

UNITED STATES PATENT OFFICE;

OTTO 'EPPENSTEIN, OF JENA, GERMANY, ASSIGNOR TO THE FIRM F CARL ZEIS, OF JENA, GERMANY.

comcIDnNonrrnLnMnTE-n.

Specification of Letters Patent. Application filed November 17, 1911.

Patented Mar. 26, 1912.

Serial No. 660,802.

To all who met may concern:

Be it known that I, O'rro Errnnsrnm, a citizen of the German Empire, residing at Jena, Germany, have invented a new and useful Coliicidence-Tclemeter, of which the following is a specification.

Theinventionrelates to uniocular telemeters having a horizontal base-line, a line of coincidence parallel to the latter, a larger,

erect and a smaller, inverted single image. ()t such tclemeters two kinds are known as regards the relative position of the single images. In the one kind the two single images are contiguousto one another only in the line of coincidence: this straight line traverses the whole field of the double image, but not the middle of the same. Inthe other kind the line of coincidence traverses approximz-itely the middle of the double image field and is completed by aboundary line, which is joined to 1ts extremities, to'

form a closed figure, the image field of the smaller single image. This image field may be entirely surrounded by that of the larger singleimage, it the extremities of the line of coincidence lie within the double image field. If they lie in the margin of this field, the larger single image field will be divided by the smaller one into two parts. The smallersingle image field is then usually given the form of a band running along the line of coincidence, two sections of the margino't' the double image field being used to complete its inclosure. As regards the position of the single images relatively to the instrument, there are also. two kinds of such telenieters known. In the first kind, which primarily is intended for so-ca-lled terrestrial objects, the smaller, inverted single image lies above the line of coincidence; 1n. the second kind, which 1s intended for so-calledaerial ob ects, this single image lies below the line of coincidence.

properties of this first one, save that the position of its single images relatively to the instrument is suitable for aerial objects, when the first double image serves for measuring terrestrial objects, and'vice versa. These demands are complied with according to the invention, by optical means being interposed in the path of the lost rays behind the separating edge, by which means the double image presented directly by these rays is suitably transposed, so as to give to it,'on the one hand, the prescribed characteristics and, on the other hand, to lay the second axis of emerging rays parallel to the first. Not counting the ocular lenses, these optical means consist of one or more lenses and of several plane reflecting surfaces or exclusively of such reflecting surfaces. In the place of two independent oculars a single one may serve for alternately viewing the two double images, by being either fixed and combined with a movable reflecting prism or itself movably disposed.

In the annexed drawing: Figure I represents adouble image field suitable for terrestrial objects, presented by a telcmeter constructed according to the invention. Fig. 2 shows a second form of such a double im age field. Fig. 8 shows a double image field suitable for aerial objects. Fig. t shows a second form of such a double image field.

Fig. 5 is .a diagram showing the optical parts of a telemeter constructed according to the invention. Fig. 6 is a section along the line 6-6 of Fig. 5. Fig. 7 shows a modification of a portion of the optical system of Fig. 5. I

In the double images according to Figs. 1 and 2 thesmallcninv'erted single image lies above the line of coincidence. In the double images according to Figs. 3 and r the smaller single image lies below the line of coincidence. The two double images according to Figs. 1 and :3 appertain to a.

telemeter having a line of coincidence traversing the whole of the double image field, those according to Figs. 2 and 4 to one having a shortened line of coincidence. In each double image field the image of a ter-' restrial object a and that of an aerial object b are each twice drawn, once as a and floated-in the right-hand telescope.

L" apymrtaining to the right-hand telescope and again as a and I) appertaining to the left-hand telescope. Where the ObjGCt-lllb age shown in full lines, it appertains to that particular single image, in the field of which it lies. Where it is shown dotted, it ap] )erta.ins to the lost portion of the other single image, and therefore not visible. The two double images for finding the range of terrestrial objects and of aerial objects, Figs. 1 and 3 and similarly Figsfl and 4. are not simultaneously visible in the instru ment with the position of the object images as shown, corresponding in either case to the completed finding-of the range. On the contrary, the transition between Figs. 1 and 3 and in the same way that between Figs. 2 and 4 necessitates, besides the change of ocular, firstly a setting of the instrui'nent as regards the vertical angle, because the terrestrial. object a and the aerial object 5 are not at. the same angular-height, and sec ondly a man'fpulat-ion of the measuring device, because the aerial object is at a greater distance than the terrestrial object. It isassumed, that the measuring device is lo- By its manipulation in Figs. 1 and 2 the smaller single image and in Figs. 3 and 4: the larger one is displaced along the line of coinci deuce, as out of the system of ray-pencils of either of the two telescopes the separating prism produces in the one double 'image field the smaller single image, in the other one the larger single image.

T he double images produced by the optical svstem of Fig. 5 may be those according to Figs. 1 and 3. The objective prism c and the objective lens (Z are the same in both telescopes. The measuring device is located in the right-hand telescope and is indicated by a shittable glass wedge e. The separating. prism consists of two prisms f and f cemented together. Between the two is located the silver separating layer g, the form and position of which may be gathered from Fig. 6. The lower margin of this layer is the separating edge. Its position above the middle plane of the telescopes causes the difference in size of the single images. ()t the two systems of ray pencils, which emerge in the direction toward the ocular it from the separating prism f f and pro duce the double image shown in Fig. 1, the upper one reflected at .the separating layer.

- r appertaius to the right-hand telescope,

the one passing through unreflected below the separating edge tothe left-hand telescope. By means of the diverse number and arrangement of the reflecting surfaces, which coact in the left-hand and in the right-hand telescope with the image revers- I ing objective (1, the above mentioned upper system produces a still inverted single imnoanaoe 7 age, whereas the lgwer system prodnceg a completely 'reiirected one. The lost rays leave the separating prism f f in the direction toward the collective lens Their lower portion z'tppertains to the right-hand, their upper portion to the left-hand telescope. On account of the absence or presenee'rcs 'iectively of reflection at the sepa-. rating layer, the single image presented directly by the (lower) rays of the right-hand telescope is completely reversed, that presented directly by the (upper) rays of the left-hand telescope shows an interchange of right and left. The so constituted doubleimage is completely reversed by the reversing lensJc, so that the double image according to Fig. 3 results, the single. image of which appertaining to the right-hand telescope is erect and lies at the top, while that appertaining to the left-hand telescope is inverted. and lies at the bottom. The re fleeting prisms Z, we and n do not alter anything in this position of thedouble image, as they otter an even number of reflections in one and the same plane. When this don ble ima e Fig. 3 is to be viewedlthrough the ocular t, the. reflecting prism 71. must be shifted into the position shown by dotted lines.

In Fig. 7 only a ridge prism 0 is interposed in the path of the lost rays, whereby 5 also the double image according to Fig. 3

is produced. At the same time two oculars 7L and h? are provided.

I claim:

1 In a horizontal coincidencetele meter two objective reflecting systems, two objec tive lenses, a separating prism system located between the objective lenses, these parts being adapted to produce a double image, the single images of which are of difterent size and the larger one of which .is erect and the smaller one inverted, optical means placed behind the separating edge of the said prism system in the path of the otherwise lost rays and adapted to transpose the double image presented by the said rays, so as to place it parallel to the first one and to arrange its single images, as regards the line of coincidence, in the opposite order to the single images in the first double image, an ocular system adapted for alternately viewing both double images and a measuring device placed on one side of the separating prism system.

2. In a horizontal co ncidence telemeter loo two objective reflecting systems, two objecl the otherwise lost rays and comprising a reversing lens for reproducing the double imalternately viewing both double images and age presented by the said rays in a plane a measuring device placed on one side of parallel to that of the first named double the separating prism system.

image, but with its single images, as re- OTTO EPPENSTEIN. E gards the line of coincidence, in the oppo- Witnesses:

site order to the single images in the first PAUL KRfiGER,

double image, an ocular system adapted for FRITZ SANDER. 

